It has become generally accepted in the trade that containers which contain beverage and food products will have a label thereon. Many different systems are presently used to apply the labels to the containers. Some of these systems will apply the label to the container after it has been filled and sealed. Other systems utilize the prelabeled container which is then filled with the product and sealed before distribution.
The present invention is most closely associated with the systems that prelabel the containers before they are filled with a product.
Prior art systems which prelabel containers are known, and one such system which has received considerable acceptance is that disclosed in U.S. Pat. No. 3,802,942, issued to Amberg et al and assigned to the Assignee of the present application. This patent teaches the forming of labels from heat shrinkable plastic that is formed of a film-foam combination plastic that is fed in an oriented sheet form to a vacuum transfer head. The labels are preprinted and cut into lengths as they are received on the transfer head which then delivers the individual labels to a plural sleeve on a mandrel and forms a seam where the ends overlap. Containers are simultaneously processed by being preheated and indexed over the sleeve supporting mandrels. The sleeves are telescopically assembled on the containers and then, together, are transported through a heat shrink tunnel. The plastic sleeve shrinks into snug surface fit with respect to the container.
As can be seen by reading the foregoing U.S. Patent and U.S. Pat. No. 3,767,496, issued Oct. 23, 1973, which discloses the overall process that the apparatus of U.S. Pat. No. 3,802,942 will perform, the forming of a tightly conforming, heat shrunk label on a container, such as a glass bottle, is not a simple task. To prevent wrinkling of the label and consequent distortion in the graphics of the label, it is necessary to apply the label to the bottle in a careful manner. The ends of the label must come into registry so that the label will not seem to be askew. When the label is to be a heat-shrinkable plastic, the ends have to overlap and be firmly sealed together to form a seam that will withstand the stress that is produced when the label shrinks.
When it seemed desirable to make the labeled container without having the label formed into a seamed sleeve before applying it to the container, systems were designed to use the bottle or container itself as the mandrel and then wind the label about the bottle and seal the overlapped ends. This sytem has been disclosed in several recent U.S. patents, including U.S. Pat. No. 4,574,020, issued Mar. 4, 1986, to H. R. Fosnaught and assigned to the Assignee of the present case.
In a still more recent U.S. Pat. No. 4,832,774, issued May 23, 1989, of common Assignee and inventorship with the present application, a system of labeling bottles is disclosed where a label is held by a vacuum head which advances into opposing relationship with a linearly moving bottle. In a timed sequence, the label has its ends pushed about the bottle until they become overlapped, at which time a heater bar engages the overlap to heat seal the label ends together. The bottle with surrounding label is then passed through a heat zone to shrink the label into external conformity with the bottle.
One problem that has arisen with the operation of the above-described apparatus under U.S. Pat. No. 4,832,774 has been the tendency of the overlapped ends of the labels to move out of vertical registry when the machine is operated at high speeds. While a perfectly good label is produced most of the time, the out-of-registry of the overlapping ends can produce a label that does not have a perfect appearance and thus does detract from the aesthetics of the label. This may occur when operating at increased labeling speeds.
The use of vacuum heads to engage labels during transfer of labels to bottles is described in U.S. Pat. No. 3,222,240 to Carter et al, dated Dec. 7, 1965. In this patent the vacuum heads at either side of the central holder are used to maintain tension on the labels during application to avoid wrinkling. The labels must actually slip relative to the heads in order for the labels to be applied to a curved surface without tearing them. This required slippage can result in misalignment of the labels with the bottle axis, but this is not critical since the labels are not complete wrap-around labels and misalignment will not be apparent.
With the foregoing in view, the present invention is one which will overcome the problems found in the prior art systems.